In the agricultural industry, seeds are frequently harvested at moisture levels that inhibit safe and long term storage of the seeds. While high moisture content inhibits safe and long term storage, crops are harvested with moisture content to help prevent seeds degradation from things such as, for example, insects, diseases, exposures (such as weather), or the like.
The high moisture content of the harvested seeds inhibits safe, long-term storage. Thus, the high moisture seeds are artificially dried to bring the seeds down to an acceptable moisture level. The drying process occurs under controlled conditions to maximize the quality of the seed products. Controlled drying conditions are necessary because the rate and temperature of drying can influence the seeds' germination and storability.
One type of conventional apparatus and method for drying moist seeds includes placing the moist seeds in a bin. The moist seeds form a seedbed above a bottom of the bin. The bottom of the bin typically contains perforations or holes. Placing the bins over a plenum allows hot, dry air to be forced up through the perforations in the bottom of the bin and through the seedbed. The hot, dry air removes moisture from the moist seeds making them dry seeds. Alternatively, the bins can be placed in a drying chamber, here air is heated and circulated within the chamber, similar to an oven. In either case, the seeds need to be stirred or agitated to effectuate even drying. In some apparatuses, the bins are moved over various airflows using conveyor belts.
Another type of seed dryer is a two-pass dryer. A two-pass dryer typically has hot air from an upper plenum forced through the seed from the top to the bottom. The air passes through the perforations in the bottom of the bin and enters a lower plenum. The pass through the seeds reduces the air temperature and increases the relative humidity. The lower temperature, higher humidity air from the lower plenum is directed to a second bin. The air passes through bottom perforations in the second bin, passes through a second seedbed from bottom to top and is typically exhausted to the atmosphere. Similar to the above, the seeds need to be stirred or agitated to effectuate even drying.
The perforations at the bottoms of the bins typically are as large as possible to permit maximum airflow with minimum resistance, but the size of the perforations is limited by the size of the seeds being dried. Thus, for a single dryer to dry multiple types of seeds, the perforations, which are typically contained in a screen, need to be changed with each seed change. Further, seeds still log in the perforations causing reduced flow and potential seed damage, and requiring cleaning of the perforations.
Thus it would be desirable to design an improved seed dryer.